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- # Copyright (c) 2009 Michael Fellinger m.fellinger@gmail.com
- # Rack::Reloader is subject to the terms of an MIT-style license.
- # See COPYING or http://www.opensource.org/licenses/mit-license.php.
- require 'pathname'
- module Rack
- # High performant source reloader
- #
- # This class acts as Rack middleware.
- #
- # What makes it especially suited for use in a production environment is that
- # any file will only be checked once and there will only be made one system
- # call stat(2).
- #
- # Please note that this will not reload files in the background, it does so
- # only when actively called.
- #
- # It is performing a check/reload cycle at the start of every request, but
- # also respects a cool down time, during which nothing will be done.
- class Reloader
- def initialize(app, cooldown = 10, backend = Stat)
- @app = app
- @cooldown = cooldown
- @last = (Time.now - cooldown)
- @cache = {}
- @mtimes = {}
- extend backend
- end
- def call(env)
- if @cooldown and Time.now > @last + @cooldown
- if Thread.list.size > 1
- Thread.exclusive{ reload! }
- else
- reload!
- end
- @last = Time.now
- end
- @app.call(env)
- end
- def reload!(stderr = $stderr)
- rotation do |file, mtime|
- previous_mtime = @mtimes[file] ||= mtime
- safe_load(file, mtime, stderr) if mtime > previous_mtime
- end
- end
- # A safe Kernel::load, issuing the hooks depending on the results
- def safe_load(file, mtime, stderr = $stderr)
- load(file)
- stderr.puts "#{self.class}: reloaded `#{file}'"
- file
- rescue LoadError, SyntaxError => ex
- stderr.puts ex
- ensure
- @mtimes[file] = mtime
- end
- module Stat
- def rotation
- files = [$0, *$LOADED_FEATURES].uniq
- paths = ['./', *$LOAD_PATH].uniq
- files.map{|file|
- next if file =~ /\.(so|bundle)$/ # cannot reload compiled files
- found, stat = figure_path(file, paths)
- next unless found && stat && mtime = stat.mtime
- @cache[file] = found
- yield(found, mtime)
- }.compact
- end
- # Takes a relative or absolute +file+ name, a couple possible +paths+ that
- # the +file+ might reside in. Returns the full path and File::Stat for the
- # path.
- def figure_path(file, paths)
- found = @cache[file]
- found = file if !found and Pathname.new(file).absolute?
- found, stat = safe_stat(found)
- return found, stat if found
- paths.find do |possible_path|
- path = ::File.join(possible_path, file)
- found, stat = safe_stat(path)
- return ::File.expand_path(found), stat if found
- end
- return false, false
- end
- def safe_stat(file)
- return unless file
- stat = ::File.stat(file)
- return file, stat if stat.file?
- rescue Errno::ENOENT, Errno::ENOTDIR
- @cache.delete(file) and false
- end
- end
- end
- end
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